JPH0799432A - Solid-state relay - Google Patents

Abstract

PURPOSE:To provide a solid-state relay applying on/off control to an output of a DC power supply having a high current duration characteristic whose output state is independently of the polarity of an output terminal of the power supply. CONSTITUTION:The solid-state relay is provided with a photo MOS relay 1 having two contacts, two transistors (TRs) 2, 3 whose bases are connected to the contacts of the photo MOS relay 1 and rectifiers each connected in parallel between an emitter and a collector of each TR in a polarity from the emitter to the collector. Since the TR is inserted between an output terminal of a DC power supply and the contact of the photo MOS coupler, the current duration characteristic of an output section is enhanced. Since the photo MOS coupler having two contacts is employed and the TR and the rectifier are connected to each contact respectively in the opposed polarity especially, the solid-state relay controlling the output independently of the polarity of the output of the DC power supply is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid state relay, and more particularly to a solid state relay for controlling the output of a DC power source on / off.

[0002]

2. Description of the Related Art As a method for controlling the output of a DC power supply by turning on and off by a signal from the outside, a contact of a solid state relay is connected to the output terminal of the DC power supply and a control signal is input from the input terminal of the relay, A method of turning on / off the output of the DC power supply is used.

[0003]

Conventionally, in this type of solid-state relay, a photo coupler or a photo-moss relay is used at the contact portion of the solid-state relay. In general, photocouplers and photomos relays have a small withstand current characteristic of the contacts themselves connected to the output terminal of the DC power supply, so that the current value of the DC power supply that can be on / off controlled is naturally limited in the conventional solid state. In addition, if the current exceeds the permissible current, the photo MOS relay or the like may be damaged.

Therefore, the conventional solid-state relay has a problem that it is not suitable for a DC power supply in which a large current flows through the output contact portion.

[0005]

In order to eliminate the above-mentioned drawbacks, the solid-state relay of the present invention is a solid-state relay in which the output of a DC power source is controlled to be turned on and off. It is characterized by including a means for turning on / off each contact and at least two transistors.

In particular, the bases of the two transistors are respectively connected to the two contacts of the means for turning them on and off.
Of the two transistors, the emitter of the first transistor is connected to one end of the output terminal, and the first rectifier is connected in parallel from the collector of the first transistor to the emitter. , The emitter of the second transistor is connected to the terminal of the output terminal to which the emitter of the first transistor is not connected, and the second rectifier is connected in parallel from the collector of the second transistor to the emitter It is characterized by being.

Further, the means for turning on / off the contact point according to the input signal is a photomos relay or a photocoupler.

If a transistor whose contact is connected to the base is connected between the output terminal of the DC power supply and the photoMOS relay, a large current flows to the output terminal even if a small current flows through the contact due to the current amplification effect of the transistor. Since the current can flow, the output of the DC power supply can be controlled by a small current output from the contact of the photo MOS relay.
Furthermore, a transistor is connected to each contact of the photomos relay having two contacts with the base side facing, the output terminal of the DC power supply is connected to the emitter of each transistor, and the rectifiers are connected in parallel from the collector to the emitter. By being connected, the output can be controlled without depending on the polarity of the output of the DC power supply. That is, in the first transistor whose emitter is connected to the terminal on the higher potential side of the two output terminals, a current flows from the emitter to the collector, and the current is further paralleled from the collector of the second transistor to the emitter. A current flows to the terminal on the low potential side through the second rectifier connected to.
When the polarity is reversed, a current flows from the emitter of the second transistor to the collector, contrary to the above, and the current flows through the first rectifier connected in parallel with the first transistor. Therefore, in either case, the solid state relay will function effectively.

[0009]

An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram of an output control circuit for a DC power source according to an embodiment of the solid state relay of the present invention. The photomos relay 1 has two contacts, and each contact has a first transistor 2 and a second contact.
The bases of the transistors 3 are connected to each other.
The emitters of the first and second transistors are respectively connected to the output terminals of the DC power supply. Further, the collectors of the first and second transistors 2 and 3 are connected to each other, and further, the first rectifying diode 7 is provided in the first transistor 2 from the collector to the emitter, and the second rectifying diode 7 is also provided. Similarly to the transistor 3, second rectifying diodes 8 are connected in parallel from the collector to the emitter.

Further, in this embodiment, resistors 4 and 5 are inserted between the collectors of the first transistor 2 and the second transistor 3 in order to shift the potential level. Further, the two contacts of the photo-MOS relay 1 are connected to each other on the sides that are not connected to the first and second transistors 2 and 3, and this connection portion and the first and second transistors are connected to each other. A resistor 6 for limiting the current is inserted between the connection portions of the collectors of the transistors 2 and 3. A diode may be used in place of the resistors 4 and 5 for the element that shifts the potential level in the above configuration.

Next, the operation of the solid state relay having such a configuration will be described.

The output of the DC power source is performed by inputting a signal to the input terminal of the photoMOS relay 1 to operate the relay to open and close the contacts, as in the conventional solid state relay. The photo-MOS relay 1 of this embodiment has two contacts and is opened / closed simultaneously by an input signal.
Transistor 2 between both contacts and the output terminal of the DC power supply,
3 is connected.

On the other hand, although it is possible to add a circuit for determining the polarity of the output of the DC power supply inside the DC power supply, such a circuit is generally provided inside the DC power supply for reasons such as economy. Is often not provided. If a transistor is simply connected between the photoMOS relay 1 and the output terminal for such a DC power source, the transistor can flow current only from the emitter to the collector. In the opposite case, it will not work effectively. The solid-state relay of the present invention can be operated without depending on the polarity even for a DC power supply whose polarity is reversed.

The operation principle of the solid state relay of the present invention in the case where the polarities are reversed as described above will be described. Now, in FIG. 1, it is assumed that the polarity of the DC power supply connected to the output side of the solid-state relay is such that the output terminal on the side currently connected to the first transistor 2 is at a high potential. At this time, when the contact portion of the photo-MOS relay 1 becomes conductive, the base current flows only in the first transistor 2 and the first transistor 2
Becomes conductive. Then, on the output side of the solid-state relay, since the power source of the polarity for driving the first transistor 2 is inserted, the first transistor 2, the resistor 4, and the second rectifying diode 8 which are in the conductive state are inserted.
An electric current flows through it. As a result, PhotoMOS relay 1
When is on, the solid state relay is on.

Next, when the polarity of the power source applied to the output side is changed and the contact portion of the photo-MOS relay 1 becomes conductive, the base current flows only in the second transistor 3 and the second transistor 3 3 becomes conductive. Then, the second transistor 3, the resistor 5, which is in the conductive state,
And a current flows through the first rectifying diode 7. As a result, the solid-state relay is turned on when the photomos relay 1 is turned on even when the polarity of the power source is changed.

As described above, when the photo-MOS relay is turned on, either the first transistor 2 or the second transistor 3 is always turned on depending on the polarity of the power source on the output side. It is possible to always make the conductive state independent of the polarity of the power source. Further, since the transistor is connected to the photo MOS relay, the withstand current characteristics are improved as compared with the photo MOS relay alone. For example, in the conventional solid-state relay consisting of a single photo-MOS relay, the output voltage of the DC power source is at most 20 even if a contact having a large withstand current characteristic is used.
Although the limit was about 0 mA, if the solid state relay of the present embodiment is adopted and, for example, a transistor having a current amplification factor of 10 is used, a solid state relay having a withstand current characteristic of about 2 A can be realized.

In the above-described embodiment, the structure in which the emitters of the two transistors are connected to the output terminal is shown. However, as shown in FIG. 2, the collector side of each transistor is connected to the output terminal. However, the same effect can be obtained.

[0019]

As described above, in the solid state relay of the present invention, the capacity of the output section can be increased by providing the transistor between the output terminal of the DC power supply and the contact of the photoMOS relay. it can. This makes it possible to control the output of the DC power supply through which a large current flows through the output terminal section.

In particular, by using a photo-moss coupler having two contacts and connecting a transistor and a rectifier to each of these contacts in directions facing each other, output control can be performed without depending on the polarity of the output of the DC power supply. A solid state relay that can be realized can be realized.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of a solid state relay of the present invention.

FIG. 2 is a circuit diagram of another embodiment of the solid state relay of the present invention.

[Explanation of symbols]

 1 Contact Photomos Relay 2 First Transistor 3 Second Transistor 4,5 Resistor 6 Resistor 7 First Diode 8 Second Diode

Claims (5)

[Claims] 1. A solid state relay for controlling the output of an output terminal of a DC power source on / off, a means for turning on / off two contacts according to the input signal, a means for turning on / off, and a means for turning on / off the output terminal. In between
A solid-state relay characterized by comprising at least two transistors. 2. A base of a first transistor of the two transistors is connected to a first contact of the two contacts, and an emitter of the first transistor is connected to one end of the output terminal. A first rectifier is connected in parallel from the collector to the emitter of the first transistor, and the base of the second transistor of the two transistors is the second of the two contacts. Connected to the contacts,
The emitter of the second transistor is connected to the terminal of the output terminal to which the emitter of the first transistor is not connected, and the second rectifier is parallel from the collector to the emitter of the second transistor. The solid-state relay according to claim 1, wherein the solid-state relay is connected to. 3. A base of a first transistor of the two transistors is connected to a first contact of the two contacts, and a collector of the first transistor is connected to one end of the output terminal. A first rectifier is connected in parallel from the collector to the emitter of the first transistor, and the base of the second transistor of the two transistors is the second of the two contacts. Connected to the contacts,
The collector of the second transistor is connected to the terminal of the output terminal to which the emitter of the first transistor is not connected, and the second rectifier is parallel from the collector to the emitter of the second transistor. The solid-state relay according to claim 1, wherein the solid-state relay is connected to. 4. The two contacts are turned on by the input signal.
The solid state relay according to claim 1, wherein the means for turning off is a photo-mos relay. 5. The two contacts are turned on by the input signal.
The solid-state relay according to claim 1, wherein the means for turning off is a photocoupler.